If River had played Jack in Titanic...
It's been mentioned in another thread that J. Cameron considered RP for Titanic.
http://www.imdb.com/name/nm0000203/board/nest/248508165?p=2
Do you think his portrayal of Jack would have been substantially different than Leo D.'s or very similar? Would he have had any chemistry with Kate Winslet? Would all the girls who reportedly saw the film multiple times have done the same with River as the lead?